Printing hammer rebound preventing means



Jan. 13,1953, M. WILLIAMS ETAL I 2,625,100

PRINTING HAMMER REBOUND PREVENTING MEANS Filed Jul 24, 1947' EnvntorsHARRY M WILLIAMS AND JAMES E. J HNSON By W Their (Ittorneg i 'atentedJan. 13, 1953 2,625,100 7 PRINTING HAMIWER REBOUND PREVENTING MEANSHarry M. Williams, Oakwood, and James E. Johnson, Dayton, Ohio,assignors to The National Cash Register Company, Dayton, Ohio, acorporation of Maryland Application my 24, 1947, Serial No. 763,352

11 Claims. (Cl. 101-93) This invention relates to improvements in meansto prevent rebound of spring-actuated printing hammers used in cashregisters and calculating machines.

The principal object of the invention is to provide means to preventspring-actuated printing hammers from rebounding after making a printingstroke, to thereby avoid blurred impressions caused by an overprintingdue to the rebounding of the printing hammer.

A specific object of the invention is to loosely mount a specifiedweight on the free end of a spring-actuated printing hammer to dampenthe action of the printing hammer after it is rapidly returned to itsnormal position.

With these and incidental objects in view, the invention includescertain novel features of construction and combinations of parts, theessential elements of which are set forth in'appended claims and apreferred form or embodiment of which is hereinafter described withreference to the drawing which accompanies and forms a part of thisspecification.

Fig. 1 is a sectional View of one form of the invention, taken on linell of Fig. 2.

Fig. 2 is a side view of one embodiment of the printin hammer and typecarrier, together with the actuating mechanism for the printing hammer.

Fig. 3 is a sectional view of another form of the invention.

. Fig. 4 is a sectional view taken on line 44 of Fig. 5, and showsanother form of the invention.

Fig. 5 is a fragmentary view of the form of invention shown in Fig. 4,together with a portion of the type carrier.

. Fig. 6 is a sectional view of another form of the invention.

Fig. 7 is a fragmentary side view of the form of the invention shown inFig. 6, together with a portion of the type carrier.

, Fig. 8 is another form of the invention taken on line 88 of Fig. 9.

, Fig. 9 is a fragmentary side view of the invention shown in Fig. 8,together with a portion of the type carrier.

In general In printing hammer mechanisms of the type herein disclosed,the hammer is actuated by a. powerful spring, which when released forcesthe hammers against the type carriers with a sudden blow. In this formof printing mechanism, when the hammer falls back to its normal positionit reacts against the driving spring, which causes the hammer torebound, and in some instances this rebound is sufiicient to cause asecond impression to be made. In the present application, one form of aspring-actuated mechanism is disclosed for the purpose of illustration;however many other forms of actuating mechanism may be provided, such asthat shown in the patent to Robertson 1,613,129.

In order to prevent the rebound of the hammer, the present inventionprovides a loosely mounted weight on the free end of the hammer, whichacts as a counteracting means to prevent the hammer from being actuatedthe second time, after the impression has been made. When the hammer isoperated by its spring to effect a sudden blow on the type carrier theloosely mounted weight moves up against the under side of the hammer andwhen the hammer drops back to its normal position this weight drops toprevent the hammer from rising the second time. Fig. 1 shows a barguided on studs as a counterweight. Fig. 3 shows a form of the inventionin which powdered metal is used for the counterweight. Fig. 4 shows around bar within the hollow head of the printing hammer. Fig. 6 showsmetal shot in the hollow head of the printing hammer, and Fig. 8 isillustrated with mercury in the hollow head of the printing hammer.Whatever form the invention takes it is only necessary that thecounterweight is loosely mounted so that it is free to move on the headof the hammer when the printing impact takes effect.

It has been found through experiment that the most eificient weight tobe applied to the free end of the printinghammer should be equal toapproximately 50% of the weight of the hammer when measured at theprinting line of the hammer.

The present invention provides a simple and effective method ofpreventing the rebound, and eliminates the use of mechanism, such asarresting pawls, as shown in Robertson supra, thus simplifying theconstruction of the rebound preventing means.

Detailed description As illustrated in Fig. 2, the printing hammer I0 ispivoted on a stud II and normally rests on a plunger [2, which isactuated by a spring [3. The plunger l2 and spring l3 are carried by aflange I4 mounted on the frame of the machine. The printing hammer I0 isprovided with a cam follower block I5 which engages a cam l6 mounted ona cam shaft IT. The free end of the hammer is provided with a rubberplaten I8, which carries a ribbon and the record receiving means againstthe type carriers l9 when the printing hammer is impelled in a clockwisedirection. The type carriers 19 are supported on a suitably locatedshaft 20.

As shown in Figs. 1 and 2, the printing hammer head 2| is provided witha pair of guiding studs 22, on which is loosely mounted a weight 23, thelatter also having a noise-dampening material 24, mounted on the upperside thereof. The block 23 is loosely mounted on the studs 22, so thatit can freely slide thereon.

When the machine is operated the cam I5, rotating in a counterclockwisedirection, engaging the follower block 15, rotates the hammer l first ina counterclockwise direction, thus compressing a spring I3. When thestep 25 of the cam 16 passes beyond the follower block 15, the spring [3rapidly rotates the hammer ID in a clockwise direction around the shaftH to impel the hammer platen 13 against the type carrier by a suddenblow. The impact of the platen 18 against the type carrier suddenlyarrests the hammer head 2!, which causes the block 23 to rise on thestuds 22 until arrested by the underside of the head, whereupon thehammer lil immediately is restored toward its normal position. Duringthis counterclockwise movement of the hammer head 2i the block 23remains in contact with the underside of the hammer head 2i. When thehammer it strikes the plunger I2, the spring will be slightly compressedand the tendency will be to impel the hammer again in a clockwisedirection and in some instances this clockwise movement is suflicient tomake a second impression. However, at this moment the weight 23 drops,thus opposing the action of the counterclockwise movement of theprinting hammer to prevent the second or rebounding printing from takingplace.

Figure 3 shows a. modified form of the invention in which the head 2| ofthe printing hammer is hollow and contains the proper amount of powderedmetal (ii. A plate 26 covers the opening 21 through which the powderedmetal is inserted into the hollow opening of the head. During theoperation of the printing hammer the powdered metal acts in the samemanner as the blocks 23v to oppose the rebound action of the printinghammer,

Figs. 4 and 5 disclose a. still further modificae tion of the inventionand show a steel rod 28 mounted in the hollow head of the printinghammer.

Figs. 6 and 7 show a still further modification of the invention,wherein the hollow head 2! of the printing hammer is provided with metalshot 29.

Figs. 8 and 9 illustrate a still further modification of the invention,wherein the hollow head 2| is provided with an appropriate quantity ofmercury 36.

In each of the modified forms of the invention' the weights 28, 29, 3Bor 3|, are maintained in the hollow head of the printing hammer by aplate 26, in the same manner as that described for the powdered metal inFig. 3. In all forms, while the weights vary in character, they are allcarried by the free end of the hammer and perform the same function.

While the form of mechanism herein shown and described is admirablyadapted to fulfill the objects primarily stated, it is to be understoodthat it is not intended to confine the invention to the one form orembodiment herein disclosed, for it is susceptible of embodiment invarious forms all coming within the scope of the claims which follow.

What is claimed is:

1. The combination of an impression hammer, type carriers located abovethe impression hammer, an actuator to impel the hammer against theunderside of the type carriers, said hammer thereafter being free tofall back from the type carriers, and a dampening means consisting of aweight freely carried by the hammer so that when the hammer is arrestedby striking the underside of the type carriers the weight is impelledagainst the under side of a surface on the hammer to dampen the returnmovement of the hammer, said weight thereafter being free to fallgravitationally to prevent rebound of the hammer toward the typecarriers.

2. The combination of a pivoted impression hammer, type carriers locatedabove the impression hammer, an actuator to impel the hammer from anormal position to a position against the underside of the typecarriers, said hammer thereafter being returned toward normal position,and a weight freely carried by the free end of the pivoted hammer forrelative bodily movement of the weight in the direction of printingmovement of the free end of the pivoted hammer when the hammer isarrested by striking the underside of the type carriers for taking animpression, said relative movement of the weight causing the weight toengage the hammer when the hammer returns toward its normal position,and said weight thereafter being free to fall back gravitationally toprevent rebound of the hammer toward the type carriers.

3. The combination of an impression hammer, type carriers located abovethe impression hammer, an actuator for impelling the hammer from anormal position against the underside of the type carriers, and a weightfreely carried by the free end of the hammer, said weight being normallyheld in engagement with the hammer by gravitation, but being free to beimpelled by momentum force in the direction of printing movement of thefree end of the hammer to engage the hammer when the hammer returnstoward normal position after an impression from the type carriers hasbeen taken to prevent rebound of the hammer after the impression hasbeen taken, said weight thereafter being free to fall backgravitationally.

4. The combination of an impression hammer, type carriers located abovethe impression hammer, an actuator for impelling the hammer from anormal position into a position against the underside of the typecarriers, a hollow head on the hammer, and means loosely carried in thehollow head of the hammer acting as a weight, the cubic contents of saidmeans being less than the cubic area of the interior of the hollow headto permit free movement of the means in the hollow head by momentum whenthe hammer is impelled against the underside of the type carriers, saidmoving means engaging the hammer as the hammer returns toward normalposition, and said means thereafter being free to fall backgravitationally, to prevent rebound of the hammer after the impressionhas been taken.

5. The combination of an impression hammer, type carriers located abovethe impression hammer, an actuator for impelling the hammer from anormal position into a position against the underside of the typecarriers, a hollow head on the hammer, and means comprising a pluralityof discrete particles carried in the hollow head of the hammer, saidmeans occupying less than all of the hollow space in the hollow headwhereby the means is free to move within the hollow head by momentumwhen the hammer is impelled against the underside of the type carriersto take an impression, said moving means engaging the hammer as thehammer returns toward normal position, and said means thereafter beinfree to fall back gravitationally, to prevent rebound of the hammerafter the impression has been taken.

6. The combination of an impression hammer, type carriers located abovethe impression hammer, an actuator for impelling the hammer from anormal position into a position against the underside of the typecarriers, and a dampening means consisting of a loose shiftable mass ofmaterial carried by said hammer, said mass shiftable relatively to thehammer in one direction by momentum when the hammer is impelled againstthe underside of the type carriers to take an impression, and said massengaging the hammer as the hammer returns toward normal position, andsaid mass thereafter being free to fall back gravitationally, to preventrebounding of said hammer after said impression has been taken.

7. The combination of an impression hammer, type carriers located abovethe impression hammer, an actuator for impelling the hammer from anormal position into a printin position against the underside of thetype carriers, and inertia means normally held on the hammergravitationally and movable with the hammer and also relatively to thehammer and acting on the hammer when the hammer changes its direction ofmovement to dampen oscillations of the hammer and prevent hammerrebound, said inertia means being free to fall back gravitationally whenthe hammer returns to its normal position.

8. The combination of an impression hammer, type carriers located abovethe impression hammer, an actuator for impelling the hammer from anormal position into a printing position against the underside of thetype carriers, and inertia means normally held on the hammergravitationally and movable with and also relatively to the hammer andacting on the hammer during their relative movements to dampenoscillations of the hammer and prevent hammeqrebound, said inertia meansbeing free to fall back gravitationally when the hammer returns tonormal position, said hammer having a platen at the free end thereof,and said inertia means being carried by the hammer adjacent the free endthereof.

9. The combination of an impression hammer, type carriers located abovethe impression hammer, an actuator for impelling the hammer from a.normal position below the type carriers into a position against theunderside of the type carriers, a hollow head on said hammer, and ashiftable mass of material in said hollow head, said mass shiftablewithin said hollow head by momentum when the hammer is impelled againstthe underside of said type carriers, said mass thereafter being free tofall back gravitationally to prevent rebounding of said hammer after theimpression has been taken and the hammer is restored to normal position.

10, The combination of an impression hammer, type carriers located abovethe impression hammer, an actuator for impelling the hammer from anormal position below the type carriers into a position against theunderside of the type carriers, a hollow head on said hammer, and ashiftable mass of material in said head, said mass of material receivingan impetus of movement in the direction of the printing movement or thehammer within the hollow head when the hammer is impelled against theunderside of the type carriers by said actuator, said mass dropping bygravity afte the impression has been taken and the hammer returns tonormal position to prevent rebounding oi the hammer.

11. The combination of an impression hammer, type carriers located abovethe impression hammer, an actuator for impelling the hamme from a normalposition below type carriers to a printing position against theunderside of the type carriers, a hollow head on said hammer, and a massof material in fluid state, occupying less than the entire hollow headso as to be movable therein by the force of momentum when the hamme isimpelled against the underside of the type carriers, and said materialacting by gravity to prevent said hammer from rebounding after theimpression has been taken and the hammer returns to normal position.

HARRY M. WILLIAMS. JAMES E. JOHNSON.

REFERENCES CITED The following references are of record in the iile ofthis patent:

UNITED STATES PATENTS Number Name Date 422,276 Wirshing Feb. 25, 1890664,011 Beresford Dec. 18, 1900 1,073,340 Fu-rman Sept. 19, 19151,613,129 Robertson -Jan. 4, 1927 1,615,976 Going Feb. 1, 1927 1,652,057Shipley Dec. 6, 1927 1,908,140 Going May 9, 1933 1,981,034 GabrielsonNov. 20, 1934 2,117,451 Robertson May 17, 1938 2,199,265 Lohrey Apr. 30,1940 2,204,187 Ostler June 11, 1940 2,208,050 Pasinski July 16, 19402,267,915 Henry Dec. 30, 1941 2,318,465 Chollar May 4, 1943 2,342,082Klosterman Feb. 15, 1944 2,353,057 Mills July 4, 1944

